Ram not showing in windows Vista Hp (FIXED)

[pwta]

I have a compaq presiro c500 laptop. It cam out with 512 ddr2 ram. I have upgraded it with 2Gb (2x1Gb) The ram shows up in bios. It shows up when I do a hardware scan. But it dosnt show up in Windows Vista. It only shows the first 512Mb out of the 2Gb.And I know its not seeing it because it is as slow as. I have checked what I can like Memtest. chkdsk and SFC. Any ideas on this one. I have also changed the ram to different ones. (I run a computr repair business.) I have never seen this problem before. Thanks

Peter

 

[geekapproved]

Which Presario C500? There's about 20 different model of C500, need to know the exact model number such as C500EU or C509NR.

Is this DDR2-667?

 

[pwta]

Its a C554tu Thats the only thing listed on the bottom.

 

[Pyree]

Msconfig>boot>advance option and make sure that the maximum memory option is unchecked

 

[pwta]

Best answer selected by pwta.

 

[pwta]

Thanks heaps, Worked a treat....